Check out data.gov.uk. They have APIs for lots of data for almost everything including legislation, schools and roads.

    http://data.gov.uk/linked-data

Here is a road:

    http://transport.data.gov.uk/doc/road/A454

Jenni Tennison writes on her blog about the use of RDFa, Microdata, URLs, versioning of URLs and other interesting topics:

    http://www.jenitennison.com/blog/node/140
    http://www.jenitennison.com/blog/node/141